Pregnancy makes your foot longer, wider, and flatter

A new University of Iowa study confirms what many women have long suspected – that pregnancy permanently changes the size and shape of a woman's feet.

Flat feet are a common problem for pregnant women. The arch of the foot flattens out, possibly due to the extra weight and increased looseness (laxity) of the joints associated with pregnancy. The new study, published in the March issue of the American Journal of Physical Medicine & Rehabilitation, suggests that this loss of arch height is permanent.

The researchers found that for about 60 to 70 percent of the women in the study, their feet became longer and wider.

Specifically, the study showed that, on average, arch height and measures of arch rigidity decreased significantly comparing early pregnancy with five months after childbirth, causing corresponding increases in foot length (between 2 and 10 mm) and arch drop. However, no significant change in the distribution of foot pressure was detected. The study also suggested that first pregnancies may account for most of the observed changes, while second, third, or higher pregnancies may not further alter foot structure.